The enneagram is a unique combination of ancient wisdom and modern psychological research that describes the entire range of human personality. In this book, Don Riso and Russ Hudson, two prominent enneagram scholars, present an in depth review of the personality types with self-assessment questionaires to help you determine your type. There are also suggestions and exercises that each of the personality types can use to achieve personal spiritual growth and greater personal satisfaction.
This book has an excellent organization and offers a wealth of insight into human behavior. Not all people think the same way - and this book can help you predict how your friends and coworkers will react in certain situations. Once you understand your own personality, you can identify your strengths and weaknesses in particular situations and set goals to overcome recurrent dysfunctional behavior patterns that are holding you back. Figure out the personality type of your significant other and you will gain insight into the recurrent conflicts within your relationship (and how to address them in a positive way!). Figure out the personality type of your boss, and you can understand the interpersonal friction that might be holding you back in your professional life.
This book is like a dozen self-help books in one and a handle that you can use to decide whether the generic advice in other popular literature will work for you or not. This is one of the few books that I can wholeheartedly say is life transforming. The guidelines for spiritual growth are ecumenical and compatible with all religious traditions.